What will happen if I was charged with a misdemeanor a years ago and still have not been convicted?

If you have a 3 year old case then surely you have a lawyer representing you?! Talk with your lawyer! Generally, I tell people that if they can, let sleeping dogs lie. There is no statute of limitations issue because the charge is filed so the statute is tolled. You could create a federal speedy trial issue (there is no right to speedy trial in state law) but you would have to demand a trial now, something that may not be in your best interest. As the case grows older, witnesses forget and move on in their lives. If you are not negatively affected, I would not stir the pot.